Drum brakes have two components, a shoe and a lining. There are three attachment methods used today to secure the lining to the shoe these methods are commonly referred to as riveted, bonded and molded. The molding process is commonly referred to as integrally molded or IM. The integrally molded process used today molds the prepped shoe in a press, which is typically hot and the friction material is held at a pressure while the heat cures resins of the friction material and the adhesive located between the shoe and the friction material.
The length of time under at which the friction material is under pressure in the press and in order to completely cure the friction material is greater than 30 seconds and may be as long as 3-8 minutes or even longer. Moreover, certain high curing temperatures are required to be maintained during this process. Accordingly, the length of time to attach and completely cure the lining to the shoe impacts tooling costs, tooling lead times, throughput, and capital requirements. Moreover, tooling costs also increase as the pieces per cycle increase. For example, integrally molded process costs depend on cure length times, required pressures and available tonnage in press, and area in press as well as required temperatures and availability of heat sources. Tooling lead times are based on the complexity of the part geometry, number of pieces per cycle and the number of tooling sets required to support a part number. Throughput is impacted by much of the same as tooling, material pressure requirements, press tonnage capacity and area in press. Also, the number of presses may increase due to high pressure demands set by the materials used. Capital requirements increase due to support equipment needed in the pressing operations based on press size, capacity and cure length.
Accordingly, it is desirable to provide a system and method for manufacturing integrally molded drum brakes at an increased capacity while reducing capital costs.